DC motors are known in the art. Various control system implementations in a variety of architectures typically depend on a DC motor as the prime motive force. For example, a DC motor may serve to rotate or translate a panel, structure, or related device.
Designers continually face the challenge of packaging and power density with respect to DC motors. Designers typically must strive to put as much power for as low cost in as small volume as possible. In almost every control system product, a cost Pareto analysis will reveal that the most costly single component is the motor, just as it is the prime constraint to achieving a certain level of performance. In the past twenty years, motor drive electronics have been reduced dramatically in terms of size and price to enable unprecedented capability for a given package size. However, there have been no significant improvements in DC motor technologies. Many current actuation systems face an immediate need for small, high power, low cost motors, and face with price targets that present day technologies may not meet.
For example, brushless DC (BLDC) motors require more touch labor to produce as they become smaller. This is primarily because of the difficulty of winding many turns of fine wire in the slots of the stator. The best winding fill that can be produced goes towards 50% or less as the slots become smaller. Also, the motor constant (torque/root-watt) gets smaller and smaller, becoming unacceptable at some point. The performance in actuation systems also suffers as the motor gets smaller because of the reduction in bandwidth resulting from the relationship of torque diminishing faster than inertia. Thus, for the smallest actuation systems, the BLDC motors become too expensive, too sluggish, or both.
As a result, in the realm of small actuation systems, brush motors have become the motor of choice. This has been primarily on the basis of motor rotor diameter versus motor overall diameter. The performance is better than equal size BLDC motors, but frequently is not good enough. The smallest brush motors are likewise very expensive for the same reasons, and also suffer from brush noise and lack of reliability. The brushes and commutator bars pose potential problems during long storage and over-demanding environments.
In view of the aforementioned shortcomings associated with motor design for small actuation systems, there is a strong need in the art for a motor suitable for use in small actuation systems without sacrificing cost and/or performance. Moreover, there is a strong need in the art for a method of making such a motor.